Systems and methods for implanting an implantable cardiac monitor

ABSTRACT

Systems and methods are provided for implanting an implantable cardiac monitor. An insertion system includes an implantable cardiac monitor (ICM). An insertion housing comprises a passage extending from a first end of the insertion housing to a second end of the insertion housing. The passage configured to receive the obturator and a receptacle in communication with the passage and an external environment. The receptacle configured to receive the ICM. An obturator is configured to move within the passage when the obturator is moved relative to the insertion housing. The obturator has a channel forming section at a distal end thereof and a motion limiter is provided on at least one of the shaft and the insertion housing.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to implantable cardiac monitors(ICMs), and more particularly to systems and methods for implantingICMs.

BACKGROUND

Implantable cardiac monitors (ICMs) are devices that may be implantedunder a patient's skin to continuously monitor the patient's cardiacactivity. An ICM may be programmed to detect and record cardiacinformation and episodes such as atrial/ventricular tachycardia, atrialfibrillation, bradycardia, asystole, etc. Triggers for detecting andrecording an event (e.g., such a Tachy/Brady detection rate, a number ofevents, and/or a duration of asystole) may be progammed by a clinician.Alternatively, when the patient experiences symptoms, the patient mayactivate the detection and recording using an external patientactivator. Diagnostics and recorded events may be downloaded by theclinician in-clinic using a programmer. Further, the data may also betransmitted to the clinician using a daily remote monitoring system.

As compared to external cardiac monitors, ICMs allow clinicians tomonitor the patient's cardiac activity for an extended period of time,with an average longevity of up to 36 months. The information recordedby ICMs enables clinicians to determine if a patient complaining ofsymptoms has irregularities in their heart rhythm that cannot beconfirmed in the clinic, particularly for transient and/or infrequentarrhythmias. The infimnation can also aid the clinician in determiningthe best course of treatment for the patient (e.g., an addition orchange of medication, a procedure such as cardioversion or ablation torestore a regular heart rhythm, and/or implantation of a pacemaker orimplantable cardioverter defibrillator for long-term treatment of anirregular heart rhythm).

ICMs are generally small (e.g., 1.1-1.5 cm³ in volume), and can beimplanted using a small incision (e.g, 1 cm). Once inserted under thepatient's skin, the ICM has a slim profile, mitigating patient concernsof comfort and aesthetics/body image. The ICM may be implanted in thepatient's chest area near the sternum, and the implant procedure maytake less than 2 minutes after application of a local topicalanesthesia. Further, ICMs are diagnostic tools that do not deliverpacing or shock therapies to the patient, nor do they require leads tobe implanted in the patient's heart.

At least one known method for implanting ICMs includes creating anincision, inserting a tool into the incision and rotating it to create apocket under the skin, and inserting the ICM using a obturator systemthat pushes the device in and uses the tool as a guide. However, usingat least some known insertion systems, the incision may be difficult tokeep open during the procedure. Further, it may be difficult to maneuverthe tool into the tissue to position the ICM. For patients with tauttissue, additional force may be required to insert the ICM, while forpatients with loose tissue, the ICM may move after implant if a pocketcreated for the ICM is large. Moreover, in at least some known insertionsystems, it may be difficult to push the ICM, which. typically hasrounded edges, into tissue. Finally, once the ICM is implanted, at leastsome known insertion systems are difficult to remove from the patient.

Furthermore, ICM utilize QRS detection to determine R-R intervalsutilized in connection with monitoring cardiac activity. However, ICMsystems may exhibit difficulties in detecting the R-R interval when theQRS complex has relatively low amplitude (e.g. less than approximately0.2 mV). As one example, approximately 10% of implants may experiencelow amplitude QRS complexes, particularly in connection with patientswho have larger body mass indices. Patients with an overly large bodymass index may have the ICM implanted in superficial adipose tissue thatis far removed from the heart.

Given the ease at which ICMs may be implanted, some physicians mayregard the implant of an ICM as a minor event and may not considerwhether the implant location and orientation will yield a QRS complexwith sufficient amplitude. Only later, after the implant has healed inplace, is it determined that the detected signals are too small.Thereafter, the ICM is removed and re-implanted which introduces anunnecessary procedure that is inconvenient, expensive and has at leastsome risk of infection. Other physicians may use external electrodes tomap an ideal location and orientation on the surface of the patient'sskin prior to ICM implant; however, this adds significant time to theprocedure and may not yield acceptable post-implant QRS amplitudes,which are subsequently measured subcutaneously.

In some ICMs, P-waves are captured from an EKG signal in order toprovide evidence of sinus rhythm. An absence of P-waves is used tosupport a determination as to whether a patient is experiencing atrialfibrillation (AF). In subsequent analysis of the information collectedby an ICM, when determining whether a patient is experiencing AF, it isdesirable for clinicians to view P-wave activity in the stored data inorder to facilitate diagnosis. However, discerning P-waves may hechallenging given that P-waves are relatively small features as comparedto R-waves (approximately 20 to 25% of the amplitude of an R-wave).While ensemble averaging between multiple cardiac cycles may be utilizedin an attempt to enhance P-waves, ensemble averaging utilizes additionalprocessing power and reduces the ICM longevity.

A need remains for systems and methods that address the problemsdescribed above and that are apparent from the description herein.

BRIEF SUMMARY OF THE DISCLOSURE

In accordance with embodiments herein, an insertion system is provided.The system comprises an implantable cardiac monitor (ICM). An insertionhousing comprises a passage extending from a first end of the insertionhousing to a second end of the insertion housing. The passage configuredto receive the obturator and a receptacle in communication with thepassage and an external environment. The receptacle configured toreceive the ICM. obturator is configured to move within the passage whenthe obturator is moved relative to the insertion housing. The obturatorhas a channel forming section at a distal end thereof and a motionlimiter is provided on at least one of the shaft and the insertionhousing.

Optionally, the second range represents an ICM final implant path. Themotion limiter may define an end of the ICM final implant path. A distalend of the obturator may be positioned substantially flush with thesecond end of the insertion housing when reaching the end of the ICMfinal implant path. The first range may represent a pocket formationpath. The motion limiter may include a latch arm located along a side ofa shaft of the obturator and may be at least one recessed region in thepassage. The latch arm may extend laterally outward from the side intothe at least one recessed region when the obturator moves to an end ofthe pocket formation path and when the obturator moves to an end of theICM final implant path. The motion limiter may include at least onelatch and at least one recessed region provided on the obturator and.insertion housing.

Optionally, the obturator may include a channel forming section that maybe provided at a distal end of the obturator. The channel formingsection may have a cross-section and may be sized and dimensionedsimilar to a cross-section, size, and dimension of the ICM. Theinsertion housing may include a blunt dissection barrel provided at thesecond end. The blunt dissection barrel may have a tapered edge that maybe configured to be utilized during a blunt dissection stabbing actionto form and hold-open an initial channel under patient tissue. The bluntdissection barrel may have a length that is shorter than a length of theICM. The length of the blunt dissection barrel may be no more than onethird of a length of the ICM. The system may further comprise a pullbackstop feature that may include a pin and groove provided on the insertionhousing and obturator. The pin may ride within the groove when theobturator is moved relative to the insertion housing. The pin and groovemay define a retracted range limit to which the obturator can moverelative to the insertion housing such that the obturator is notaccidentally removed from the insertion housing.

In accordance with embodiments herein, a method is provided foroperating an insertion system. The method comprises providing anobturator in a passage in an insertion housing such that the obturatorextends from a first end of the insertion housing to a second end of theinsertion housing. The method installs an implantable cardiac monitor(ICM) into a receptacle of the insertion housing. The receptacle is incommunication with the tube of the insertion housing. The obturator isconfigured to move along a first range until the channel forming sectionextends a predetermined distance from the second end of the insertionhousing. The predetermined distance is defined by the motion limiter.The obturator is configured to move along a second range in which thechannel forming section forces the ICM from the second end of theinsertion housing. Optionally, the ICM may be pre-installed into theinsertion tool before the implant procedure begins.

Optionally, the method further comprises initially positioning theobturator and insertion housing in a blunt dissection state. A bluntdissection barrel at the second end of the insertion housing is insertedin an incision to a desired depth, moving the obturator along a range ofmotion corresponding to an ICM pocket formation path until reaching afully extended position corresponding to an ICM pocket formation state.Optionally, the method may apply three to a handle of the obturator todirect a channel forming section at the distal end of the obturator toextend from the second end of the insertion housing in order to form anICM pocket.

Optionally, once the ICM pocket is formed, pulling back on the obturatoruntil the channel forming section of the obturator is positioned behindthe receptacle of the insertion housing in order to permit the ICM tomove into the insertion passage (path between the first and second endsof the insertion housing). The method may apply force to the handle ofthe obturator to direct the distal end of the obturator to discharge theICM from the second end of the insertion housing into the ICM pocket.The method may move the obturator relative to the insertion housinguntil reaching a motion limiter, the motion limiter defining at leastone of an end for a pocket forming state or an ICM final implant statefor the obturator and insertion housing.

In accordance with embodiments herein, an insertion system is provided.The system comprises an implantable cardiac monitor (ICM) includingfirst and second ICM electrodes configured to be utilized in connectionwith sensing physiologic signals, the first and second ICM electrodesseparated by an electrode spacing. A medical instrument is provided. Themedical instrument comprises a shaft with a channel preparation elementthat is configured to be inserted subcutaneously into an ICM channelregion and first and second instrument electrodes provided on thechannel preparation element and are configured to sense physiologicsignals during an ICM implant process prior to device insertion. Thefirst and second instrument electrodes are separated by the electrodespacing.

Optionally, the channel preparation element may represent a needle(e.g., a lumen built-in to the obturator) having a distal end and aproximal end. The first and second instrument electrodes may be providedon the needle at the distal and proximal ends, respectively. Conductorsmay be coupled to the first and second instrument electrodes and mayextend along the needle. The conductors may have proximal ends withcontacts configured to be electrically coupled to at least one of theICM or an external device.

Optionally, the medical instrument may further comprise a syringecoupled to the proximal end of the needle. The medical instrument mayfurther comprise a probe body that includes a receptacle configured toreceive the ICM. The receptacle may include first and second contactsspaced apart from one another and may be positioned to align with thefirst and second ICM electrodes. The first and second contacts may beelectrically coupled to the first and second instrument electrodes andmay be configured to convey physiologic signals sensed by the first andsecond instrument electrodes to the ICM. The channel preparation elementmay represent a needle with a distal end and a proximal end. Theproximal end may be coupled to the probe body. The first and secondinstrument electrodes may be provided on the distal and proximal ends,respectively, of the needle.

Optionally, the medical instrument may comprise an insertion housing.The insertion housing may comprise a passage extending from a first endof the insertion housing to a second end of the insertion housing. Thepassage may be configured to receive the obturator. The insertionhousing may further comprise a receptacle in communication with thepassage and an external environment. The receptacle may be configured toreceive the ICM. The shaft may represent an obturator configured to movewithin the passage when the obturator is moved relative to the insertionhousing. The channel preparation element may represent a channel formingsection at a distal end of the obturator. The first and secondinstrument electrodes may be provided on the channel forming section andmay be configured to collect the physiologic signals when the channelforming section is extended to a pocket formation state subcutaneouslyin the ICM channel region.

In accordance with embodiments herein a method is provided for mappingan implant location and orientation (vertical, diagonal, horizontal foran implantable cardiac monitoring (ICM) device. The method comprisesinserting a channel preparation element of a medical instrumentsubcutaneously into an ICM candidate location. The method sensesphysiologic signals at instrument electrodes located along the channelpreparation element, utilizes one or more processors to analyze acharacteristic of interest from the physiologic signals relative to asignal criterion, and designates the ICM candidate location as a finalICM implant location based on the analysis of the characteristic ofinterest.

Optionally, the method may further comprise maintaining the channelpreparation element at an ICM candidate position and orientation whilesensing the physiologic signals. The method may record the physiologicsignals at the ICM. The ICM may analyze the characteristic of interestfrom the physiologic signals. The method may record the physiologicsignals to the ICM. The ICM may designate whether the ICM candidatelocation qualifies as a final ICM implant location.

Optionally, the method further comprises conveying the physiologicsignals to the ICM. The ICM may convey the physiologic signals to anexternal device. The external monitoring device may perform theanalyzing operation. The channel preparation element may represent aneedle having a distal end and a proximal end. The instrument electrodesmay be provided on the needle at the distal and proximal ends. Themethod may comprise conveying the physiologic signals from theinstrument electrodes to at least one of the ICM or an external device.The medical instrument may comprise a probe body. The method may insertthe ICM into a receptacle provided in the probe body where ICMelectrodes on the ICM engage contacts within the receptacle. The RN mayrecord the physiologic signals sensed by the instrument electrodes.

The foregoing and other aspects, features, details, utilities andadvantages of the present disclosure will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic view of one embodiment of an implantable cardiacmonitor (ICM) insertion system in accordance with embodiments herein.

FIG. 1B illustrates the insertion housing and obturator from an oppositeside to the view shown in FIG. 1A in accordance with embodiments herein.

FIG. 2A illustrates a side view of the blunt dissection barrel formed inaccordance with an embodiment. herein.

FIG. 2B illustrates a top plan view of a portion of the insertionhousing and obturator joined to one another to better illustrate thepullback stop feature in accordance with embodiments herein.

FIG. 2C illustrates a top plan view of a portion of the insertionhousing and obturator to show the motion limiter when in the firstposition in accordance with embodiments herein.

FIG. 3A illustrates a portion of the insertion housing and obturatorwhen the obturator is at an ICM intermediate implant state in accordancewith embodiments herein.

FIG. 3B illustrates a portion of the insertion housing and obturatorwhen the obturator is inserted to an ICM final implant state inaccordance with embodiments herein.

FIG. 4A illustrates a pocket formation state, at which the obturator isextended through the insertion housing in accordance with embodimentsherein.

FIG. 4B illustrates an ICM loading state, at which the obturator issubstantially withdrawn from the insertion housing, in accordance withembodiments herein.

FIG. 4C illustrates an ICM final implant state in accordance withembodiments herein.

FIG. 5A illustrates a manner in which the system of FIGS. 4A-4C may beheld in the user's hand in accordance with embodiments herein.

FIG. 5B illustrates a manner in which the system of FIGS. 4A-4C. may beheld in the user's hand in accordance with embodiments herein.

FIG. 6A illustrates an insertion system formed in accordance with analternative embodiment and utilized perform implant location mapping inaccordance with embodiments herein.

FIG. 6B illustrates a manner in which the system of FIG. 6A may be heldin the user's hand in accordance with embodiments herein.

FIG. 6C illustrates a manner in which the system of FIG. 6A may be heldin the user's hand in accordance with embodiments herein.

FIG. 7 illustrates the medical instrument, with the ICM installed intothe receptacle in accordance with embodiments herein.

FIG. 8 illustrates a medical instrument formed in accordance with analternative embodiment for mapping.

FIG. 9 illustrates a medical instrument formed in accordance with analternative embodiment for mapping.

FIG. 10 illustrates a method for mapping an implant location andorientation for an ICM device in accordance with embodiments herein.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure provides systems and methods for implanting animplantable cardiac monitor (ICM). An insertion system includes animplantable cardiac monitor, an obturator and an insertion housing. Theinsertion housing includes a barrel extending from a first end of theinsertion housing to a second end of the insertion housing, the barrelconfigured to receive the ICM and the obturator. Embodiments hereininclude one or more of various unique features described hereafter.

Referring now to the drawings and in particular to FIGS. 1A and 1B, anICM insertion system is indicated generally at 100. Components ofinsertion system 100 include an insertion housing 102, an obturator 104and an ICM 108. In FIGS. 1A and 1B, the components of insertion system100 are shown separate from one another (i.e., in a disassembled state).In FIGS. 4A-4C, the components of insertion system 100 are shown in anassembled state.

Insertion housing 102 includes a barrel 109, with a passage therethrough, that extends from a first/proximal end 110 to a second/distalend 112. In this embodiment, barrel 109 has a substantially rectangularcross section. Alternatively, barrel 109 may have any shape that enablesinsertion system 100 to function as described herein.

The passage 107 extends along a length of the barrel 109 of theinsertion housing 102. The passage 107 has a cross-section thatsubstantially conforms to the cross-section of the ICM 108. The passage107 includes inner dimensions (width and thickness) that are similar to,but slightly larger than, the outer dimensions (width and thickness) ofthe ICM 108, such that ICM 108 can be positioned within, and movablealong, the passage 107. The first end 110 includes an opening 114 tofacilitate inserting the obturator 104 into insertion housing 102. Thedistal end 112 includes a discharge opening 164, from which the ICM 108is discharged into a channel under a patient's tissue when the ICM 108is ejected by the distal end 166 of the obturator 104. Example shapesfor the distal end 112 are discussed below in more detail in connectionwith FIG. 2A.

A tip is formed at the distal end 166 of the obturator 104. The tip isshaped and dimensioned to perform blunt dissection in subcutaneoustissue of the patient as th.e obturator 104 is extended from the distalend 112 of the insertion housing 102. In the illustrated embodiment, thetip ha.s a tapered conical shape. Alternatively, the tip may have anyshape that enables obturator 104 to function as described herein. Forexample, the tip may have an oval shape, a duckbill shape, a wedgeshape, a hook shape, and/or any other suitable shape. The obturator 104may be fabricated from, for example, polycarbonate, polysulfone, oranother similarly resilient material. In some embodiments, for comfortand/or usability, the handle 106 of the obturator 104 or ribs 103 isformed from a softer material (e.g., silicone).

The barrel 109 includes a central receptacle section 111, joined at oneend to a blunt dissection barrel 113 and at another end to a proximalsection 115, all formed integral with one another. The proximal segment115 includes a pair of wings 101 that extend in opposite directions fromthe barrel 109. They wings 101 are configured to be held between twofingers, such as the index finger and middle while the user's thumb orpalm of the hand press on the handle 106. For example, the wings 101 maybe concave similar to a syringe to facilitate holding the tool similarto a syringe. The blunt dissection barrel 113 is shaped and dimensionedto be utilized during a blunt dissection stabbing action to form aninitial channel under the skin at an incision location. The proximalsection 115 and receptacle session 111 include a peripheral contour thatfacilitates gripping by a user during operation. The receptacle section111 includes an ICM reception cavity 154 therein. The receptacle cavity154 is configured to receive the ICM 108 during an implant process. TheICM reception cavity 154 is shaped and dimensioned to conform to a shapeof the ICM 108, and as such has a length and width substantially similarto, but slightly larger than the length 152 and width 156 of the ICM108. For example, the receptacle cavity 154 may have a length ofapproximately 40-50 min and a width of 5-10 m. Optionally, alternativedimensions may be utilized based on the size of the ICM 108. Thereceptacle section 111 includes a length that is at least slightlylonger than the length 152 of the ICM 108. The reception cavity 154includes one or more detents 155 extending inward from a perimeterthereof. The detents 155 may be aligned with one another or misalignedrelative to one another. The detents 155 are configured to resistremoval of the ICM 108 once the ICM 108 is inserted into the receptioncavity 154, such that detents 155 prevents the ICM 108 frominadvertently falling out of the the reception cavity 154 and from beingdropped onto a nonsterile surface such as the floor. The receptioncavity 154 is located directly above and in communication with a portionof the passage 107 that passes through the receptacle section 111. Thereception cavity 154 has a depth that is sufficient to hold the ICM 108while the obturator 104 is located in the passage 107 directly below theICM 108.

The blunt dissection barrel 113 extends from the receptacle section 111toward the distal end 112. The blunt dissection barrel 113 is formedwith a length 158 that is short in relation to the overall length 152 ofthe ICM 108. By way of example only, a length 158 of the bluntdissection barrel 113 may be approximately ¼ or ⅓ of the length 152 ofthe ICM 108. Alternatively, the blunt dissection barrel 113 may belonger or shorter. in the present embodiment, the blunt dissectionbarrel 113 is formed relatively short in order to simplify certain typesof insertion processes. In addition, by utilizing a short bluntdissection barrel 113, the system 100 avoids forming an unduly largechannel. in which the ICM 108 may ultimately shift, During the implantprocess, the blunt dissection barrel 113 is inserted (e.g. through ablunt dissection stabbing action) into an incision until the skin abutsagainst a leading edge 160 of the receptacle section 111.

FIG. 2A illustrates a side view of the blunt dissection barrel 113formed in accordance with an embodiment herein. As shown in FIG. 2A, thedistal end 112 of the blunt dissection barrel 113 includes a taperededge 162. The tapered edge 162 tapers relative to a side profile of theblunt dissection barrel 113. Optionally, the tapered edge 162 may beoriented to taper in alternative directions. Optionally, the taperededge 162 can also have different contours, such as curved profile, as ameans to facilitate gradual introduction of the barrel through theincision site to minimize trauma to the tissue. FIG. 2A also illustratesa step up in the height at the leading edge 160 at the intersectionbetween the blunt dissection barrel 113 and the receptacle section 111.During an implant operation, the blunt dissection barrel 113 is inserteduntil skin at the point of incision abuts against the leading edge 160.

FIG. 1B illustrates the insertion housing 102 and obturator 104 from anopposite side to the view shown in FIG. 1A. FIG. 1B also illustrates anend view of an ICM 108. The ICM 108 includes a width 156 and thickness170. By way of example, the ICM 108 may have a length of approximately40-50 mm, a width of 5-10 m, and a thickness of 2-5 mm. The foregoingdimensions are merely an example, and other shapes and sizes may beutilized. In the present example, the ICM 108 has a rectangularcross-section with rounded edges. Optionally, the ICM 108 may havealternative cross-sections (e.g., square, tubular, polygon shaped, ovalshaped and the like).

The obturator 104 includes an elongated shaft 168 that is elongated toextend from the handle 106 to a distal end 166. The shaft 168 may beshaped. with various cross-sections. For example, the shaft 168 may beshaped with a rectangular cross-section that is sized and dimensioned tobe similar to the rectangular cross-section of the ICM 108. The shaft168 includes a beveled shape at the distal end 166, where the beveledshape joins a channel forming section 172. The channel forming section172 joins a main body section 174 that extends along a substantialmajority of the shaft 168 to the handle 106, The main body section 174has a lateral width 176 that is greater than a lateral width 178 of thechannel forming section 172. A smooth taper 180 is provided at thetransition point between the main body and channel forming sections 174and 172. By way of example, it may be desirable to provide the channelforming section 172 with a smaller cross-sectional envelope as comparedto the cross-sectional envelope of the ICM 108, to facilitate thecreation of a pocket with a desired size into which the ICM 108 isultimately to be implanted. For example, the channel forming section 172may have a slightly smaller width and thickness (as viewed in thecross-section), as compared to the width and thickness of the ICM inorder that the It 108 will fit snugly into the pocket when inserted andavoid undue risk of shifting within the pocket.

The insertion housing 102 and obturator 104 include one or more pullbackstop features that are configured to limit an extent to which theobturator 104 is retracted from the insertion housing 102 during apullback operation.

FIG. 2B illustrates a top plan view of a portion of the insertionhousing 102 and obturator 104 joined to one another to better illustratethe pullback stop feature. In the embodiment of FIGS. 1B and 2B, thepullback stop feature include a groove 182 that is provided along one orboth sides of the shaft 168 of the obturator 104. The pullback stopfeature also includes a pin 184 provided on a lever arm 183 formed withthe barrel 109 of the insertion housing 102. The pin 184 extends inwardinto the passage 107 and is configured to align with the groove 182. Thepin 184 rides within the groove 182 when the obturator 104 is linearlyslid or moved relative to the insertion housing 102 within the passage107. The arm 183 is flexible and biased inward toward the passage 107 tomaintain the pin 184 engaged with the groove 182. The arm 183 may beflexed outward during assembly to permit the obturator 104 to beinitially loaded into the passage 107. The groove 182 includes aretracted range limit 188. Optionally, the pin 184 may be molded as onesolid piece with the lever arm 183.

The retracted range limit 188 is positioned at a point along a side ofthe obturator 104, such that the obturator 104 is able to be pulled backsufficiently that the distal end 166 clears the receptacle section 154,thereby allowing the ICM 108 to drop from the receptacle 154 into thepassage 107. The pin 184 engages at least the retracted range limit 188in order to prevent the obturator 104 from being entirely removed fromthe insertion housing 102. The pullback stop feature facilitates animplant process to become smoother as the user need not know when thepullback operation is completed, thereby removing uncertainty. Thepullback stop feature also prevents the obturator 104 from inadvertentlyfalling out of the barrel 109 and from being dropped onto a nonsterilesurface such as the floor.

The insertion housing 102 and obturator 104 also include a forwardmotion limiter 190 (FIGS. 2C, 3A and 3B) that is configured to permitand limit forward movement of the obturator 104 within the barrel 109over different ranges of motion during different stages of the ICMinsertion process. During the pocket formation stage, the motion limiter190 is moved over a first range to a first position, where the motionlimiter 190 limits an amount to which the channel forming section 172 onthe obturator 104 extends beyond the distal end 112 of the insertionhousing 102. Accordingly, the motion limiter 190 defines a distance(channel formation range of motion) by which the channel forming section172 extends from the distal end 112. Optionally, the motion limiter 190may be removed and instead, the handle 106 may be configured to hitproximal end 110 to define the distance corresponding to the channelformation range of motion. During an final implant state, the motionlimiter 190 is moved over a second range to a second position, where themotion limiter 190 maintains the channel limning section 172 within thebarrel 109 of the insertion housing 102. During the ICM final implantstate, the motion limiter 190 prevents the channel forming section 172from being discharged from the distal end 112. The motion limiter 190 isconfigured to prevent the user from pushing the ICM 108 deeper than thedesired relative to the end of the blunt dissection channel (defined bythe blunt dissection barrel 113).

FIG. 2C illustrates a top plane view of a portion of the insertionhousing 102 and obturator 104 to show the motion limiter 190 when in thefirst position. With reference to FIGS. 1B and 2C, the motion limiter190 is provided on at least one of the shaft 168 and/or the interiorwall of the passage 107 in the insertion housing 102. The motion limiter190 includes a latch arm 192 that extends laterally outward from a sideof the shaft 168.

The latch arm 192 includes a distal tip 194 that, when in a relaxedunbiased position, extends laterally beyond a lateral envelope definedby the side 196 of the shaft 168. The latch arm 192 is configured to bedeflected inward and outward (toward and away from the shaft 168) alongdirections denoted by arrow A. When deflected inward (i,e. pressed inintentionally by the finger of the user), the latch arm 192 moves to aposition within a side envelope of the side 196, allowing obturator 104to he repositioned along passage 107 of the insertion housing 102.

The motion limiter 190 also includes a recessed region 198 that isprovided at a select point along the interior wall of the passage 107.The insertion housing 1.02 includes one or more recessed regions 198provided along one or both sides of the passage 107. The lever arm 192slides along the interior wall of the passage 107 until deflectingoutward into one of the recessed region 198. FIG. 2C illustrates thelatch arm 192 engaged within the recessed region 198. When the obturator104 is fully inserted into the barrel 107, the latch arm 192 to flexlaterally into the recessed region 198. The distal tip 194 of the leverarm 192 engages a wall of the recessed region 198 to prevent furtherforward movement (in the direction of arrow B) of the obturator 104,relative to the insertion housing 102. The recessed region 198 ispositioned along the passage 107 a predetermined distance from thedistal end 112 such that, when the latch arm 192 engages the recessedregion 198, a predetermined length of the obturator extends from thedistal end 112. In the present example, the recessed region 198 ispositioned along the passage 107 such that the channel forming section172 of the obturator 104 extends beyond the distal end 112 when thelatch arm 192 engages the recessed region 198.

Optionally, the range of forward movement may be limited by the handle106 of the obturator when stopped against the insertion housing 102.

The position of the latch arm 192 along the shaft 168, and/or therecesses region 198 along the passage 107 may be changed to adjust anamount of the obturator 104 that extends beyond the distal end 112 ofthe insertion housing 102. Optionally, the latch arm 192 may be locatedon the wall of the passage 107 and the recessed region 198 located onthe shaft 168. Optionally, alternative motion limiting structures may beused in place of, or in addition to, the latch arm 192 and recessedregion 198.

In addition, the cooperation between the recessed region 198 and thelatch arm 192 afford a secondary purpose, namely to allow the latch arm192 to assume a relaxed unbiased position while the obturator is fullyinserted into the insertion housing 102 during storage and shipment. Byallowing the latch arm 192 to maintain a relaxed position, withoutexperiencing lateral loading during storage, embodiments herein avoid“creep” (also referred to as loss of lateral force) of the latch arm 192into a deformed condition. When the latch arm 192 loses the lateralforce or creeps, the latch arm 192 no longer engages the recessed region198 and at least partially inhibits the operation of the motion limiter190. When the latch arm 192 is not within the recessed region 198, thelatch ani 192 exhibits a lateral friction force on the wall of thepassage 107. The lateral friction force facilitates maintaining theobturator 1.04 in any given position relative to the insertion housing102.

Optionally, a knob or other ergonomically appealing feature may beprovided on the handle 106. For example, a knob may be added to thehandle 106 in order that a user may hold the insertion barrel 109between a thumb and forefinger while palming the obturator handle. Theforegoing arrangement enables the user to maintain the obturator 104 ina fully inserted position in the barrel 109 during the blunt dissectionaction.

FIG. 3A illustrates a portion of the insertion housing 102 and obturator108 when the obturator 104 is at an ICM intermediate implant state. FIG.3B illustrates a portion of the insertion housing 102 and obturator 104when the obturator 104 is inserted to an ICM final implant state. FIG.3B also illustrates a portion of the barrel 109 cut out (along line D)to illustrate internal features within the insertion housing 102 at theproximal end 110.

In the position illustrated in FIG. 3A, the latch arm 192 is entirelyremoved from the proximal end 110 of the barrel 109. When entirelyremoved, the latch arm 192 flexes laterally outward in the direction ofarrow C until extending beyond a lateral envelope 191 defined by theside 196. The lateral envelope 191 extends along the side 196. Theobturator 104 is inserted into the insertion housing 102 in thedirection of arrow B until reaching the position. illustrated in FIG.3B.

In the position illustrated in FIG. 3B, the latch arm 192 is receivedwithin the proximal end 110 of the insertion housing 102. A proximalrecessed region 193 is provided at the proximal end 110. The proximalrecessed region 193 is terminated at a ledge 195 that is located at abeginning of the passage 107. When the obturator is inserted to the ICMfinal implant state, the distal tip 194 of the latch aim 192 engages theledge 195 to prevent further insertion of the shaft 168. When the latcharm 192 engages the ledge 195, the user recognizes that the distal end166 (FIG. 1A) of the obturator 104 is proximate to the distal end 112 ofthe insertion housing 102 and has fully discharged the ICM 108. Theledge 195 is formed in the recessed region 193 to catch the latch arm192. By providing the recessed region 193, the system 100 prevents thelatch arm 192 from flaring further outward in the event pressure isapplied to the obturator 104. Additionally, ledge 195 may he angled bydesign to deflect latch arm 192 outward and harder into recess 193 suchthat if the user forcefully advanced the obturator 104 in direction B,there would be increased force locking the latch arm 192 into recess193, rather than latch arm 192 “slipping” into passage 107.Additionally, the angle of ledge 195 and the angle of latch arm 192 maybe designed to take advantage of the column strength of latch arm 192when pressed in recess 193

Optionally, the recessed region 193 and ledge 195 may be formed as anotch that receives the tip 194 of the latch arm 192.

The foregoing example describes a motion limiter that includes a latcharm that extends laterally outward from a side of the shaft of theobturator 104 when the obturator moves to an end of the pocket formationpath and when the obturator moves to an end of the ICM final implantpath. in the foregoing example, the motion limiter includes a latch aimand at least two recessed regions 198 and 193. Optionally, additionallatch arms may be utilized and one or more than two recessed regions maybe utilized to form the motion limiter. As a further option, a firstlatch arm may be utilized to define the end of the pocket formationpath, while a second latch arm is utilized to define an end of the ICMfinal implant path. Optionally, the latch arm or arms may be provided onthe interior wall of the passage 107 and oriented to deflect into thepassage 107, while recessed regions are provided along the side of theshaft 168 of the obturator 104.

The insertion housing 102 may be relatively firm to maintain its shapeas insertion housing 102. is inserted into the incision. Accordingly,insertion housing 102 and obturator 104 may be fabricated from, forexample, polycarbonate, polysulfone, or another similarly resilientmaterial. The obturator handle 106 may be fabricated from, for example,polycarbonate or silicone. Various ergonomic features may be utilizedsuch as using more grip-friendly materials. Additionally oralternatively, as another grip-friendly feature, the wings may be formedon the insertion housing and ribs may be formed on the housing, all or aportion of which may be made with a urethane or other high-frictionmaterial. To assemble insertion system 100, as shown in FIG. 4A, theobturator 104 is fully inserted (fully closed position) into insertionhousing 102, and ICM 108 is inserted into insertion housing 102.Insertion system 100 may be packaged and distributed to clinicians in afully assembled (i.e., pre-loaded) configuration, as shown in FIG. 4A.Alternatively, the components of insertion system 100 may be assembledon-site where the implantation procedure is to take place. Once ICM 108is inserted into receptacle 154, detents 155 (also refened to asprojections) prevent ICM 108 from falling out of the receptacle 154 intoambient environment. For example, the detents 155 may engage ICM 108 ina snap-fit engagement to maintain ICM 108 in receptacle 154. As shown inFIG. 4A, when ICM 108 is inserted into receptacle 154, the obturator 104is already inserted into the passage 107 and traverses the receptaclesection 111. Accordingly, obturator 104 initially prevents the ICM 108from entering the portion of the passage 107 within the receptaclesection 111. Optionally, the ICM may be pre-installed into the insertionhousing 102 before the implant procedure begins. A method of implantingICM 108 using insertion system 100 will now be described with respect toFIGS, 4A-4C. An incision (e.g., a 6-12 millimeter (mm) incision) is madein the patient using, for example, a surgical scalpel. The obturator 104and insertion housing 102 are initially positioned, relative to oneanother, in a blunt dissection state 402 (as shown in FIG. 4A). When inthe blunt dissection state 408, the distal end 166 of the obturator 104is extended to project from the distal end 112 of the insertion housing102. The distal end 166 of the obturator 104 is inserted through theincision (denoted by dashed line 167) into the patient's tissue. Thetapered shape of distal end 166 provides a relatively small spear shapedentry point into the tissue. To push the channel forming section 172 ofthe obturator 104 further into the tissue, the clinician may rotate,torque, and maneuver the insertion housing 102. The clinician continuesto apply pressure until the distal end 112 of the insertion housing 102is inserted through the incision 167 into the patient's tissue (FIG.4B). The tapered shape of distal end 112 also provides a relativelysmall spear-shaped entry point into the tissue for the insertion housing102.

As the channel forming section 172 (and optionally, the blunt dissectionbarrel 113) is inserted to a desired depth, the user applies a force tothe handle 106 of the obturator 104 to maintain the distal end 166 ofthe obturator 104 projected from the distal end 112 of the insertionhousing 102.

Alternatively, the blunt dissection barrel 113 may be initially insertedinto the patient's tissue, with the obturator 104 partially retracted,that may also be referred to as the blunt dissection state. As a furtheroption, the obturator 104 may be retracted even further from theinsertion housing 102, such as to the positions shown in either of FIG.4C, or any intermediate position there between. When the obturator 104begins in a retracted position (during the blunt dissection state), oncethe blunt dissection barrel 113 is instered below the tissue, the distalend 166 is then extended until projecting from the blunt dissectionbarrel 113 by a desired amount, such as illustrated in FIG. 4A. Theobturator 104 moves along a range of motion corresponding to an ICMpocket formation. path until reaching a filly extended positioncorresponding to an ICM pocket formation state 402. The obturator 104moves along the pocket formation path until the channel forming section172 extends a predetermined distance from the distal end 112 of theinsertion housing 102 as shown in FIG. 4A. The predetermined distance isdefined by the motion limiter 190 when moved along the first range tothe first position (FIG. 2C).

The channel forming section 172 is shaped and dimensioned to form achannel or pocket under the patient's tissue to receive the ICM 108.Once the pocket is formed, the user withdraws the obturator 104, whileholding the insertion housing 102 in the initial position with the bluntdissection barrel 113 located under the patient tissue. The obturator104 is pulled back, relative to the insertion housing 102.

FIG. 4B illustrates an ICM loading state 404, at which the obturator 104is substantially withdrawn from the insertion housing 102. When in theICM loading state 404, the channel forming section 172 of the obturator104 is withdrawn from the proximal section 115 of the insertion housing102, until the distal end 166 is positioned outside or behind thereceptacle section 111. Once the distal end 166 clears the receptaclesection 111 of the passage 107, the ICM 108 drops into the passage 107.The ICM 108 may drop into the passage 107 due to gravity. Optionally,the user may apply a slight force with a thumb or finger to the ICM 108to ensure proper loading. The ICM 108 resides within the passage 107when in the ICM loading state 404, and is thus ready to be implanted.

FIG. 4C illustrates an ICM final implant state 406. The obturator 104 ismoved along an ICM final implant path until reaching the ICM finalimplant state 406, at which the obturator 104 is inserted by apredetermined distance into the insertion housing 102. When in the ICMfinal implant state 406, the distal end 166 of the obturator 104coincides with the distal end 112 of the blunt dissection barrel 113.When in the ICM final implant state 406, the distal end 166 of theobturator 104 has forced the ICM 108 to discharge from the bluntdissection barrel 113 and reside within the pocket under the patient'stissue. In the example of FIG. 4C, a dashed line 167 indicates a pointof incision where everything to the left of the dashed line 167 is inthe tissue past the point of incision. The ICM is 108 implanted adesired distance, for example governed by length 158 (FIG. 1A), beyondthe incision line.

To implant the ICM 108, using obturator handle 106, the clinician pushesthe obturator 104 further into insertion housing 102 such that theobturator 104 moves relative to insertion housing 102. As shown in FIGS.4A-4C, pushing the obturator 104 in turn pushes ICM 108 throughinsertion housing 102. The clinician continues to push the obturator 104until the latch arm 192 moves along the second range to the secondposition and prevents further movement, thereby defining an end of theICM final implant path. For example, as explained in connection withFIGS. 3A-3B, the latch arm 192 engages the ledge 195 to define astopping point for the insertion of the obturator 104. In theillustrated embodiment, the portion of the length of the obturator 104beyond the latch arm 192 is approximately equal to the length ofinsertion housing 102. Accordingly, as shown in FIG. 4C, when the latcharm 192 contacts the ledge 195, the ICM 108 is fully deployed (i.e., ICM108 is positioned entirely outside of insertion housing 102). Thisenables the clinician to confirm that ICM 108 is fully deployed in thetissue, even though the clinician will generally be unable to visuallyconfirm the position of ICM 108. After ICM 108 is deployed, theclinician removes insertion housing 102 from the incision and closes theincision using known closure techniques (e.g., adhesive strips, sutures,etc.).

Optionally, a knob may be provided on the handle 106 of the obturator104. The knob may be rounded informed of a somewhat flexible material,such as silicone, to be comfortable in the palm of a user when applyingforce to the obturator 104.

FIGS, 5A and 5B illustrate a manner in which the system 100 of FIGS. 1and 2. may be held in the user's hand. An index finger and middle fingerthe user's hand are positioned over the wings at the proximal end of theinsertion housing, while the user's thumb presses on the handle of theobturator, similar to the operation used with a syringe.

Optionally, an indicator may be provided to facilitate aligning theinsertion housing during an implantation procedure, as described herein.The indicator may be a colored (e.g., red) hand formed on the outside ofblunt dissection barrel. Alternatively, the indicator may be any indiciaand/or feature that enables the indicator to function as describedherein.

The ICM insertion systems and methods described herein facilitaterelatively straightforward implantation of an ICM into a patient.Specifically, the systems and methods described herein facilitatekeeping an incision propped open, maneuvering an insertion housingwithin tissue, guiding placement of the ICM, deploying the ICM such thatthere is little to no space between the ICM and the surrounding tissue,and removing the insertion housing after deployment of the ICM iscomplete.

Implant Location Mapping

Next, embodiments are described herein that may be utilized inconnection with an implant location mapping operation to determinewhether an ICM candidate location (e.g. region where the ICM is plannedto be implanted) and orientation (e.g. vertical, diagonal, horizontal)would yield physiologic signals, from which one or more characteristicsof interest can be reliably analyzed. For example, when implanting anICM to monitor cardiac activity, the characteristic of interest mayrepresent the peak of the R-wave.

During the implant location mapping operation, a medical. instrument isused to record cardiac signals. The cardiac signals are then analyzed toidentify R-waves, such as within an EKG signal. The R-waves are comparedto one or more signal criteria, such as comparing a peak of the R-waveto an R-wave threshold. When the measured cardiac signals yield R-waveshaving sufficient amplitude, the physician can determine that, if theICM is implanted in the present candidate location at the presentorientation, the ICM would yield satisfactory cardiac signals.Alternatively, if the cardiac signals do not exhibit an R-wave havingsatisfactory characteristics (e.g. an amplitude below a threshold), thephysician may determine that the present ICM candidate location and/ororientation would not yield sufficient cardiac signals. Accordingly, thephysician may choose to adjust the position of the medical instrument totest alternative ICM candidate locations. The adjustment may merelyinvolve turning the medical instrument along a longitudinal axis.Additionally or alternatively, the adjustment may involve slightly orsubstantially reorienting an angular position of the medical instrument.Additionally or alternatively, the adjustment may involve testing anentirely separate ICM candidate location.

FIG. 6A illustrates an insertion system 600 formed in accordance with analternative embodiment and utilized to perform implant location mapping.The insertion system 600 includes an insertion housing 602, an obturator604 and an ICM 608. The insertion housing 602 and obturator 604represent a medical instrument utilized in connection with performingimplant location mapping and may include some or all of the featuresdiscussed in connection with FIGS, 1-5. In the example of FIG. 6A-6C,the insertion housing 602 is provided with a different shape than theinsertion housing 102 of FIGS. 1A and 1B. Optionally, the insertionhousing 102 may be utilized with implant location mapping. Further, theinsertion housing 602 may be utilized in connection with the embodimentsof FIGS. 1A and 1B without adding the implant location mapping features.The insertion housing 602 includes a barrel 609 with a passage 607extending between a first/proximal end 610 and a second/distal end 612.The second end 612 includes an opening 614, from which the distalportion of the obturator 604 and the ICM 608 extend at various states ofthe implant process. The barrel 609 includes a central reception section611, a blunt dissection barrel 613 and a proximal section 615, similarto the configuration described in connection with FIGS. 1-5. Thereception section 611 includes a reception cavity 654 that is configuredto receive the ICM 608 during an implant process.

The insertion housing 602 includes lateral surfaces 601 and 603 that arearranged in a concave manner to form an hourglass shape with a narrowportion 603A located between opposed wider portions 601A. The lateralsurfaces 601 and 603 include ribs 603B (also referred to as verticalknurls). The concave arrangement of the lateral surface 601 and 603 andthe ribs 603B improve gip integrity between the thumb and index fingerwhen grasped by the user.

The obturator 604 includes a handle 606 that is connected to one end ofa shaft 66$. The shaft 668 extends from the handle 606 to a. distal end666. The shaft 668 includes a channel forming section 672 that isconfigured to form an ICM pocket under the tissue during the implantprocess. The channel forming section 672 represents one example of achannel preparation clement that is configured to be insertedsubcutaneously. As explained herein, additional or alternative channelpreparation elements may be utilized during the mapping operation.

In the illustrated embodiments, the channel forming section 672 has a.smaller cross-section than a remainder of the shaft 668. Optionally, thechannel forming section 672 may have the same cross-sectional.dimensions as a remainder of the shaft 668. Alternatively, the shaft 668may have smaller cross-sectional dimensions and/or a differentcross-sectional shape than the dimensions and shape of the channelforming section 672.

The ICM 608 includes a housing 620 that is attached at one end to aheader 622, and at an opposite end to a battery 624. The header 622includes at least one electrode 626 that is provided along one sidethereof. An exterior shell enclosing the battery 624 is utilized as anelectrode 628 generally denoted by dashed lines. Although, it isrecognized that a larger portion of the shell of the battery 624 may beused as the electrode 628. The electrodes 626 and 628 are generallyseparated from one another by an electrode spacing 62.7. The electrodes626, 628 may also be referred to as ICM electrodes. The ICM electrodes626 and 628 are located on a common side of the ICM 608. It should berecognized that the entire shell of the battery 624 may be utilized asan electrode, and thus, the electrode 628 may substantially surround theend of the ICM 608 in the region corresponding to the battery 624.Optionally, subsections of the shell for the battery 624 may be coveredwith insulation, while other subsections of the shell are exposed todefine discrete regions for the electrode 628. The electrode(s) 626 isprovided along one or both sides of the header 622.

The header 622, housing 620 and battery 624 cooperate to definegenerally an overall rectangular shape with rounded edges between thesides and with rounded ends 630 and 632 (although other shapes may beused). During operation, the ICM 608 performs sensing operationsutilizing the electrodes 626 and 628, in order to sense and recordphysiologic signals. Various types of physiologic signals may becollected, such as cardiac signals, respiratory signals, impedancesignals, neurological signals and the like, depending upon the locationin which the ICM 608 is positioned and the nature of the sensingcircuitry within the ICM 608.

In connection with a mapping operation, the obturator 604 includeselectrodes 634, 635 arranged along section 672 of the shaft 668. Theelectrodes 634, 635 are also referred to as instrument electrodes inorder to be distinguished from the ICM electrodes 626, 628. Theobturator 604 also includes contacts 636 and 637 that are positionedalong a main body section 673 of the obturator 604.

The instrument electrode 634 and contact 636 are electrically coupled toone another through a conductor 640, while the electrode 635 and contact637 are connected to one another through a conductor 642. The conductorsextend along or within the shaft 668. The electrodes 634 and 635 areseparated by an electrode to electrode spacing 644 that generallycorresponds to the electrode spacing 627 between the ICM electrodes 626,628. The instrument electrodes 634, 635 are separated by the electrodespacing 644 in order that the system can perform implant locationmapping during the implant process based on an electrode spacing thatconforms to the electrode spacing 627 of the ICM, but prior toimplanting the ICM.

The contacts 636, 637 are separated from one another along the shaft 668by an electrode to electrode spacing 646 that also corresponds to theelectrode spacing 627, in order that, when the ICM 608 is inserted intothe receptacle 654, the contacts 637, 636 physically and electricallyengage the ICM electrodes 626, 628.

Optionally, the electrode spacing 646 between the contacts 636, 637 maybe adjusted so long as the contacts 636,637 align with the ICMelectrodes 626, 628. Optionally, the contacts 636, 637 may be providedon one or more interior surfaces of the receptacle 654 in the insertionhousing 602. To do so, conductors are provided to couple the instrumentelectrodes 634, 635 from the obturator 604 to contacts on the insertionhousing 602.

The physiologic signals collected at the instrument electrodes 634, 635may be conveyed to the ICM 608 and/or an external monitoring device inaccordance with alternative embodiments herein. In the example of FIG.6, the physiologic signals sensed at the instrument electrodes 634, 635are conveyed to the ICM 608 through the contacts 636, 637.

FIGS. 6B and 6C illustrate a manner in which the system 600 of FIG. 6Amay be held in the user's hand. A thumb and forefinger of the user'shand are positioned within the narrow portions along the lateralsurfaces. The obturator handle 606 is held in a palm of the user's hand.The rounded end of the obturator handle 606 is configured to fitcomfortably in the palm of the hand and allow the user firm control ofthe distal end of the obturator during the blunt dissection process whenit is necessary to open tissue under the skin to make a channel for theICM.

FIG. 7 illustrates the medical instrument 605, with the ICM 608 insertedinto the receptacle 654. The ICM 608 is positioned such that theelectrodes 626 and 628 face downward toward the bottom of the receptacle654 in order to engage the contacts 637, 636 (FIG. 6) on the obturator604. Once the channel Riming section 672 is inserted subcutaneously intoan ICM candidate location, the instrument electrodes 634, 635 conveyphysiologic signals to the ICM 608. The ICM 608 may wireless convey thephysiologic signals to an external device.

The ICM 608 and/or external device may analyze the physiologic signals,such as i) to identify whether the amplitude of the P-wave satisfies aP-wave threshold, ii) to identify whether the amplitude of the R-wavesatisfies a R-wave threshold or iii) to analyze some othercharacteristic of interest. When the ICM 608 performs the analysis andthe characteristic of interest satisfies the corresponding signalcriteria, the ICM 608 may convey an indication to an external monitor(e.g. via a Bluetooth or other wireless communications link) that thepresent candidate location and orientation are satisfactory.Alternatively, the ICM 608 may convey an indication to the externalmonitor that the present candidate location and orientation are notsatisfactory. The process for mapping candidate implant locations isdescribed below in more detail in connection with FIG. 10.

FIG. 8 illustrates a medical instrument 800 formed in accordance with analternative embodiment for mapping. The medical instrument 800 includesan ICM 808 that is inserted into a receptacle 854 formed within a probebody 802. The probe body 802 is shaped similarly to an insertion housing(as described above in connection with FIGS. 1-6). Optionally, the probehousing 802 may include alternative shapes and designs. The probehousing 802 is attached to a proximal end of a needle 868. The needle868 may represent a lumen built-in to the obturator. The needle 868includes instrument electrodes 834 and 835 provided at the distal end866 and the proximal end 833. The needle 868 represents another type ofchannel preparation element 872. The needle 868 is inserted at an ICMcandidate location and with a desired orientation.

The electrodes 834 and 835 are coupled via conductors with contacts 836and 837 (denoted in hidden line) that are provided in a bottom of thereceptacle 854 in the probe body 802. The contacts 836, 837 arepositioned to align with electrodes on the ICM 808 (similar to theembodiments described above in connection with FIGS. 6 and 7).

During operation, the user inserts the needle 868 to the candidatelocation and waits for collection of physiologic signals, analysis ofcharacteristics of interest therein and a determination of whether thecandidate implant location and orientation would result in physiologicsignals of sufficient amplitude. The indication of whether the candidateimplant location is satisfactory may he provided by an external device.In response thereto, the physician continues the implant process at thepresent candidate implant location and orientation, or alternativelyremoves the needle 868 and inserts the needle at a new candidate implantlocation and/or orientation.

FIG. 9 illustrates a medical instrument 900 formed in accordance with analternative embodiment for mapping. The medical instrument 900 includesa syringe 902. For example, the syringe may he utilized to injectlidocaine or another similar substance, such as in connection withnumbing a candidate implant site. The syringe 902 is attached to aproximal end of a needle 968. The needle 968 includes instrumentelectrodes 934 and 935 provided at the distal end 966 and the proximalend 933. The needle 968 represents another type of channel preparationelement 972. The needle 968 is inserted at a candidate location and at adesired orientation.

The electrodes 934 and 935 are coupled via conductors 940 to an externalmonitoring device. Optionally, the conductors 940 may be coupled to anICM receptacle (e.g. similar to the receptacles illustrated in FIGS.1-8). The external monitoring device and/or ICM may collect physiologicsignals and perform the analysis described herein to determine whetherthe location and orientation of the needle 968 represents an acceptableimplant location. The needle 968 represents another type of channelpreparation element 972.

During operation, the user inserts the needle 968 to the candidateimplant location and waits for the ICM 808 and/or external device tocollect physiologic signals, analyze characteristics of interest thereinand determine whether the candidate implant location and orientationwould result in physiologic signals of sufficient amplitude. In responsethereto, the physician continues the implant process at the presentcandidate implant location and orientation, or alternatively removes theneedle 968 and inserts the needle at a new candidate location and/ororientation.

FIG. 10 illustrates a method for mapping an implant location for an ICMdevice in accordance with embodiments herein. At 1002, a channelpreparation element of a medical instrument is inserted subcutaneouslyat an ICM candidate location. The Channel preparation element may differbased upon the stage in the implant process or the nature of the system.For example, at 1002, a syringe with a needle (FIG. 9) may he insertedto introduce lidocaine or another numbing agent. Additionally oralternatively, a needle may be inserted that is provided on aninstrument similar to the instrument illustrated in FIG. 8. Additionallyor alternatively, the channel forming section 672 of an obturator 604(FIG. 6) may be inserted.

At 1004, physiologic signals are sensed at first and second instrumentelectrodes located along the channel preparation element. The sensedphysiologic signals may he conveyed and recorded at an ICM and/or andexternal monitoring device. For example, as illustrated in connectionwith FIGS. 6-8, the physiologic signals sensed at the instrumentelectrodes are conveyed to and recorded by an ICM that is directlyconnected to the medical instrument. Additionally or alternatively, thephysiologic signals, sensed at the instrument electrodes are conveyedthrough a wired connection to and recorded by an external monitoringdevice.

As noted herein, various types of physiologic signals may be sensed andcollected. For example, the physiologic signals may represent cardiacsignals, respiratory signals, impedance signals, neurological signals,brain waves and the like. While the illustrated embodiments utilize twoinstrument electrodes, it is recognized that more instrument electrodesmay be utilized. For example more than two instrument electrodes may beprovided along the shaft 668 of the obturator 604. When more than twoelectrodes are provided on the obturator 604, all or a subset of theelectrodes may be utilized during any individual sensing operation. Asone example, physiologic signals may be sensed and collected betweendifferent combinations of instrument electrodes at 1004, where thedifferent combinations of electrodes represent different candidatelocations. For example, when a needle is inserted with a series ofelectrodes thereon, the needle may be longer than the length of an ICM.Different combinations of the electrodes along the needle may be used tocollect physiologic signals.

An optional operation is provided at 1005. At 1005, when the physiologicsignals are conveyed from the instrument electrodes to the ICM, the ICMmay wirelessly transmit the physiologic signals to an external device(e.g. through a Bluetooth transmitter or other wireless protocol). Forexample, the external device may represent a cell phone, tabletcomputer, laptop computer, home medical monitoring device,physician-patient monitor and the like. The external device may thenanalyze the physiologic signals as described hereafter. Optionally, theICM need not transmit the physiologic signals to any external device,but instead, the ICM may perform the analysis described hereafter andmerely provide an indication regarding the results of the analysis tothe external device.

At 1006, one or more processors (within the ICM and/or an externaldevice) are utilized to analyze a characteristic of interest from thephysiologic signals relative to the signal criteria. As one example,when the physiologic signals represent cardiac signals, thecharacteristic of interest may represent one or more features of thecardiac cycle (e.g. the peak of the R-wave, peak of a P-wave, etc.). Theanalysis may involve comparing the characteristic of interest to one ormore signal criteria (e.g. one or more thresholds). As one example, eachP-wave may be compared to a P-wave threshold where the threshold definesthe minimum acceptable amplitude for the P-wave to justify the candidateimplant location and orientation. As another example, the R-waves may becompared to are R-wave threshold for a similar determination.Additionally or alternatively, other aspects of the P-wave and/or R-wavemay be compared with thresholds.

As another example, when the physiologic signal represents aneurological signal or brainwave, the characteristic of interest mayrepresent an amplitude or overall activity of evoked potentials fromnerve fibers or brain waves within a select frequency range.

Optionally, the analysis at 1006 may involve combining multiplephysiologic signals such as to develop an ensemble average over multiplecardiac cycles. The ensemble average may then be compared with one ormore thresholds.

At 1008, the characteristic of interest is compared to the signalcriteria to determine whether the signal criteria are satisfied. Whenthe signal criteria are satisfied, flow moves to 1010. At 1010, the ICMcandidate location is designated as a final ICM implant location.

Returning to 1008, when the signal criteria are not satisfied, flowmoves to 1012. At 1012, the user is informed that the ICM candidatelocation has not provided a physiologic signal that satisfies the signalcriteria. Accordingly, the user adjusts a position and/or orientation ofthe channel preparation element of the medical instrument. For example,the user may entirely withdraw the medical instrument from thesubcutaneous position and reinsert the channel preparation dement.Alternatively, the user may shift an orientation of the medicalinstrument utilizing a slight prying force and/or by rotating themedical instrument about a longitudinal axis thereof As another example,the user may partially withdraw the medical instrument to change theinsertion angle and reinsert the channel preparation element along a newtrajectory. The operations of FIG. 10 may be repeated until the signalcriteria are satisfied for the characteristic of interest.

The indication regarding whether the characteristic of interestsatisfies the signal criteria may be provided in various manners. Forexample, the external device may provide a visual and/or audibleindication to the user (e.g. yes, no, green light, red light, yellowlight, percentage compliance). Additionally or alternatively, theexternal device may provide the raw results of the analysis without adirection as to whether the present implant location is satisfactory.For example, the external device may indicate the characteristic ofinterest such as the signal strength of the physiologic signal, thenumber of P-waves and/or R-waves detected, the amplitudes of the P-wavesand/or R-waves detected, the number of P-waves and/or R-waves thatexceed a threshold, an average amplitude difference between the measuredP-waves and a P-wave minimum amplitude threshold, an average amplitudedifference between the measured R-waves and an R-wave minimum amplitudethreshold and the like. Additional or alternative indications may beprovided to infbrm the user regarding the nature of the characteristicof interest from the physiologic signal and additional informationregarding whether the present candidate implant location issatisfactory.

Optionally, the external device may provide the foregoing informationregarding the results of the analysis verbally (e.g. audibly stating asize of a QRS complex as measured in millivolts). Additionally oralternatively, the external device may audibly inform the user each timea P-wave is discerned, the number of P-waves discerned over a period oftime and/or number of cardiac cycles, and the like.

Although certain embodiments of this disclosure have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of this disclosure. All directionalreferences (e.g., upper, lower, upward, downward, left, right, leftward,rightward, top, bottom, above, below, vertical, horizontal, clockwise,and counterclockwise) are only used for identification purposes to aidthe reader's understanding of the present disclosure, and do not createlimitations, particularly as to the position, orientation, or use of thedisclosure. Joinder references (e.g., attached, coupled, connected, andthe like) are to be construed broadly and may include intermediatemembers between a connection of elements and relative movement betweenelements. As such, joinder references do not necessarily infer that twoelements are directly connected and in fixed relation to each other. Itis intended that all matter contained in the above description or shownin the accompanying drawings shall be interpreted as illustrative onlyand not limiting. Changes in detail or structure may he made withoutdeparting from the spirit of the disclosure as defined in the appendedclaims.

When introducing elements of the present disclosure or the preferredembodiment(s) thereof, the articles “a”, “an”, “the”, and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including”, and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above constructions withoutdeparting from the scope of the disclosure, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall he interpreted as illustrative and not in a limitingsense.

What is clamied is:
 1. An insertion system comprising: an implantablecardiac monitor (ICM); an insertion housing comprising: a passageextending from a first end of the insertion housing to a second end ofthe insertion housing, the passage configured to receive the obturator;and a receptacle in communication with the passage and an externalenvironment, the receptacle configured to receive the ICM; an obturatorconfigured to move within the passage when the obturator is movedrelative to the insertion housing, the obturator having a channelforming section at a distal end thereof; and a motion limiter providedon at least one of the shaft and the insertion housing.
 2. The system ofclaim 1, wherein the second range represents an ICM final implant pathand the motion limiter defines an end of the ICM final implant path, adistal end of the obturator being positioned substantially flush withthe second end of the insertion housing when reaching the end of the ICMfinal implant path.
 3. The system of claim 1, wherein the first rangerepresents a pocket formation path, the motion limiter includes a latcharm located along a side of a shaft of the obturator and at least onerecessed region in the passage, the latch an extending laterally outwardfrom the side into the at least one recessed region when the obturatormoves to an end of the pocket fonnation path and when the obturatormoves to an end of the ICM final implant path.
 4. The system of claim 1,wherein the motion limiter includes at least one latch and at least onerecessed region provided on the obturator and insertion housing.
 5. Thesystem of claim 1, wherein the obturator includes a channel formingsection provided at a distal end of the obturator, the channel formingsection having a cross-seetion and being sized and dimensioned similarto a cross-section, size and dimension of the ICM.
 6. The system ofclaim 5, wherein the channel forming section of the obturator isconfigured to be utilized during a blunt dissection stabbing action toform an initial channel under patient tissue.
 7. The system of claim 1,wherein the injector housing includes a blunt dissection barrel providedat the second end, the blunt dissection barrel is configured to beutilized during a blunt dissection stabbing action to form an initialchannel under patient tissue, the blunt dissection barrel having alength that is shorter than a length of the ICM.
 8. The system of claim7, wherein the length of the blunt dissection barrel is no more than onethird of a length of the ICM.
 9. A method for operating an insertionsystem, the method comprising: inserting an obturator into a passage inan insertion housing such that the obturator extends from a first end ofthe insertion housing through a second end of the insertion housing;inserting an implantable cardiac monitor (ICM) into a receptacle of theinsertion housing, wherein the receptacle is in communication with thetube of the insertion housing, the obturator configured to move along afirst range until the channel forming section extends a predetermineddistance from the second end of the insertion housing, the predetermineddistance being defined by the motion limiter; the obturator configuredto move along a second range in which the channel forming section forcesthe ICM from the second end of the insertion housing.
 10. The method ofclaim 9, further comprising initially positioning the obturator andinsertion housing in a blunt dissection state, when a obturator and ablunt dissection barrel at the second end of the insertion housing isinserted through an incision to a desired depth, moving along a range ofmotion corresponding to an ICM pocket formation path until reaching afully inserted position corresponding to an ICM pocket formation state.11. The method of claim 9, further comprising applying force to a handleof the obturator to maintain a channel forming section at the distal endof the obturator extended from the second end of the insertion housingto form an ICM pocket.
 12. The method of claim 11, further comprising,once the ICM pocket is formed, pulling back on the obturator until thechannel forming section of the obturator is positioned behind thereceptacle of the insertion housing in order to permit the ICM to moveinto the passage.
 13. The method of claim 12, further comprisingapplying force to the handle of the obturator to direct the distal endof the obturator to discharge the ICM from the second end of theinsertion housing into the ICM pocket.
 14. The method of claim 9,further comprising moving the obturator relative to the insertionhousing until reaching a motion limiter, the motion limiter definingatleast one of an end for a pocket forming state or an ICM final implantstate for the obturator and insertion housing.
 15. An insertion systemcomprising: an implantable cardiac monitor (ICM) including first andsecond ICM electrodes configured to be utilized in connection withsensing physiologic signals, the first and second ICM electrodesseparated by an electrode spacing; and a medical instrument, comprising:a shaft with an channel preparation element configured to be insertedsubcutaneously into an ICM channel region; and first and secondinstrument electrodes provided on the channel preparation element andconfigured to sense physiologic signals during an ICM implant process,the first and second instrument electrodes separated by the electrodespacing.
 16. The system of claim 15, wherein the channel preparationelement represents a needle having a distal end and a proximal end, thefirst and second instrument electrodes provided on the needle at thedistal and proximal ends, respectively, conductors coupled to the firstand second instrument electrodes and extending along the needle, theconductors having proximal ends with contacts configured to beelectrically coupled to at least one of the ICM or an external device.17. The system of claim 16, wherein the medical instrument furthercomprises a syringe coupled to the proximal end of the needle.
 18. Thesystem of claim 15, wherein the medical instrument further comprises aprobe body that includes a receptacle configured to receive the ICM, thereceptacle including first and second contacts spaced apart from oneanother and positioned to align with the first and second ICMelectrodes, the first and second contacts electrically coupled to thefirst and second instrument electrodes and configured to conveyphysiologic signals sensed by the first and second instrument electrodesto the ICM.
 19. The system of claim 18, wherein the channel preparationelement represents a needle with a distal end and a proximal end, theproximal end coupled to the probe body, the first and second instrumentelectrodes provided on the distal and proximal ends, respectively, ofthe needle.
 20. The system of claim 15, wherein the medical instrumentcomprises: an insertion housing comprising: a passage extending from afirst end of the insertion housing to a second end of the insertionhousing, the passage configured to receive the obturator; and areceptacle in communication with the passage and an externalenvironment, the receptacle configured to receive the ICM; the shaftrepresenting an obturator configured to move within the passage when theobturator is moved relative to the insertion housing, the channelpreparation element representing a channel forming section at a distalend of the obturator, the first and second instrument electrodesprovided on the channel forming section and configured to collect thephysiologic signals when the channel forming section is extended to apocket formation state subcutaneously in the ICM channel region.
 21. Amethod for mapping an implant location and orientation for animplantable cardiac monitoring (ICM) device, the method comprising:inserting an channel preparation element of a medical instrumentsubcutaneously into a ICM candidate location at a particularorientation; sensing physiologic signals at instrument electrodeslocated along the channel preparation element; utilizing one or moreprocessors to analyze a characteristic of interest from the physiologicsignals relative to a signal criterion; and designating the ICMcandidate location and orientation as a final ICM implant location basedon the analysis of the characteristic of interest.
 22. The method ofclaim 21, further comprising maintaining the channel preparation elementat an ICM candidate position and orientation while sensing thephysiologic signals.
 23. The method of claim 21, further comprisingrecording the physiologic signals at the ICM, wherein the ICM analyzesthe characteristic of interest from the physiologic signals.
 24. Themethod of claim 21, further comprising recording the physiologic signalsto the ICM, wherein the ICM designates whether the ICM candidatelocation and orientation qualifies as a final ICM implant location. 25.The method of claim 21, further comprising conveying the physiologicsignals to the ICM, the ICM conveying the physiologic signals to anexternal device, the external monitoring device performing the analyzingoperation.
 26. The method of claim 21, wherein the channel preparationelement represents a needle having a distal end and a proximal end, theinstrument electrodes provided on the needle at the distal and proximalends, the method comprising conveying the physiologic signals from theinstrument electrodes to at least one of the ICM or an external device.27. The method of claim 21, wherein the medical instrument comprises aprobe body, the method further comprising inserting the ICM into areceptacle provided in the probe body where ICM electrodes on the ICMengage contacts within the receptacle, the ICM recording the physiologicsignals sensed by the instrument electrodes.